I don't actually have a reason for trying to build a Linux kernel with the CONFIG_PREEMPT_RT patch set. There's no way I can even measure the impact of it. Still, I felt like having a "real-time" Linux box, and set out to make one. Little did I know how difficult it would be to even get started.

Also, on a modern multicore, don't forget the -jn option to make where n is the number of processes to run in parallel. The recommendation I usually see is to use number of cores + 1, but I don't know what the actual best value is.

Yes, the first thing that struck me was 4 hours? On a core i7? Then I saw he wrote 'make', rather than 'make -j5'. Using only one core out of 4 is quite inefficient.